When packaging a semiconductor chip after circuitry has been formed thereon, the interconnection between the circuitry on the chip and the input/output connecting pins on a package substrate may be implemented by Flip-Chip packaging technology. A Flip-Chip assembly includes a direct electric connection of a face down (that is, “flipped”) semiconductor chip onto a package substrate, such as a ceramic substrate or a circuit board. Flip-Chip technology is quickly replacing older wire bonding technology that uses face up semiconductor chips with the wire connected to each pad on the semiconductor chips.
To package a semiconductor chip using Flip-Chip packaging technology, the semiconductor chip is flipped and positioned on a package substrate. Conductive bumps are reflown to form electric connections therebetween and provide limited mechanical mounting for the semiconductor chip and the package substrate. Then, an underfilling adhesive, such as epoxy, is used to fill spaces between the semiconductor chip and the package substrate in order to provide even better mechanical interconnection between the semiconductor chip and the package substrate.